Trimaran - Especially Searunner - Owners

[Mark Johnson]

Originally Posted by md7a

Hey SeaOtterJim, how does that saildrive work for you?
Saw a 34 with a saildrive down in Napa a few years ago and was intrigued.
What make/model is it, and did you reinforce the hull around the cutout?
Does it stick up above the floorboards in the salon?
I've been noodling on the idea of a hybrid saildrive for my SR31.

I have seen exactly such a gizmo... it was an OMC saildrive (9.9 hp), which is as small and light as they come.

The floor was both doubled AND made level.

It used gasoline, so was inherently risky for that reason, as well as fuel inefficient.

Also, it was placed in the stern castle floor! It used up the best spot for a refer or ice box, and had a box above the floor for the wet exhaust's up and down elbow.

This box left little room for feet!

The engine was underpowered for the 34, and with all of these downsides, I would strongly suggest avoiding it.

PS... Compared to an OB on a sled... with an outdrive, you still have the underwater metal corrosion and hard growth issues, which you do not have on an OB motor kicked up. Also, the OB motor can be taken to the mechanic, vs bring the mechanic to the boat!

Of course... a kicked up OB motor, with "0" drag, is good for an extra knot of boat speed when sailing.

[Jimske]

Originally Posted by Mark Johnson

I have seen exactly such a gizmo... it was an OMC saildrive (9.9 hp), which is as small and light as they come.

The floor was both doubled AND made level.

It used gasoline, so was inherently risky for that reason, as well as fuel inefficient.

Also, it was placed in the stern castle floor! It used up the best spot for a refer or ice box, and had a box above the floor for the wet exhaust's up and down elbow.

This box left little room for feet!

The engine was underpowered for the 34, and with all of these downsides, I would strongly suggest avoiding it.

PS... Compared to an OB on a sled... with an outdrive, you still have the underwater metal corrosion and hard growth issues, which you do not have on an OB motor kicked up. Also, the OB motor can be taken to the mechanic, vs bring the mechanic to the boat!

Of course... a kicked up OB motor, with "0" drag, is good for an extra knot of boat speed when sailing.

OB on sled okay. A downside is being on the wrong "tack" when motoring or heading into a chop and getting too much cavitation.

Always a trade off.

[Mark Johnson]

Originally Posted by Jimske

OB on sled okay. A downside is being on the wrong "tack" when motoring or heading into a chop and getting too much cavitation.



Always a trade off.

True, motorsailing does require that one adjust the sled a bit. Motoring in a chop becomes problematic only in a really BAD chop!

I had a 9.9 Yamaha saildrive OB motor on a sled, on my SC 28, and when empty, she would motor at 10 knots! Fully loaded... 8.5 knots.

I only remember once that the chop was SOOO bad, (between Chub and Nassau), that motoring into it was a serious issue. It was blowing 25 to 30 on the nose, in a 3' nasty chop, on top of 8' waves!

I could still make headway, slowly, but had to stay below half throttle, so that when the prop jumped out of the water, it did not rev it's brains out. It was a VERY long day!

99% of the time, it was OK, even in a 2' Key West chop.

If I had long range cruising plans, on the bigger Searunners, over many years, I would go for a diesel inboard (located below the aft companionway ladder, amidships), and standard drivetrain.

The up front cost is more, but less over 20 years. Also, it is MUCH more utilitarian! I have motorsailed hard to windward, in 10' waves and 40 knots, to make landfall and seek shelter.

For just a couple of years of cruising, on the 25 or 31'er, especially if money up front counts, the OB on a sled will get you out there, with less utility, but more sailing speed, and less drivetrain maintenance.

On the 34,37, or 40' ers, I would go with the diesel, or nothing at all. You can still sister up with a RIB and putz up a river, albeit very slowly.

[smj]

Here's our Marples designed sled. We have a 15hp Honda that will reach mid 7's at WOT and lets us cruise easily at about 6kts. This is on a Marples designed Searunner 38 catamaran. No problem with cavitation yet and we made the outboard steerable with the tiller bar.

[Mark Johnson]

Originally Posted by smj

Here's our Marples designed sled. We have a 15hp Honda that will reach mid 7's at WOT and lets us cruise easily at about 6kts. This is on a Marples designed Searunner 38 catamaran. No problem with cavitation yet and we made the outboard steerable with the tiller bar.Attachment 156773Attachment 156774

Great job AJ! Look me up when you are in town... [emoji1365]

[smj]

Originally Posted by Mark Johnson

Great job AJ! Look me up when you are in town... [emoji1365]

[emoji1303]will do. May be heading up that way with the boat this spring.

[Sea Otter Jim]

My saildrive is a yanmar 3gm 30d direct water cooling not fresh water . No problems at all it was installed in 1985 and still runs great.It's under the aft cabin table and is Ver easy to work on.its a lot quitier than a regular shaft drive and no vibration . I get a lot of compliments on how quiet it is.It's the early model so only 22hp but I cruise at 6 knots at half a gallon per hour.I had a 31 with an outboard on the transom.I wouldn't want one in a 31 as its to small and would take up too much room.My 31 was built for hustler magazine in 78 and had the aft cabin extended all the way to the transom just like the 37ft.It didn't have the anchor locker for stern hook.It made a huge difference as to the inside living space.It would also make a big difference in the 34 ft searunner.The 31 just seems too small for an inboard diesel.I was very happy with my honda 10hp longshaft.I put close to 18,000 miles on her in Mexico in 5 years.The big difference in the 31vs 37 is the hobby horsing it's all a trade off . I miss my 31 when I haul out.

[snort]

I'm curious to know about the hobbyhorsing and if there is anything to do to counteract that.

[owly]

Originally Posted by snort

I'm curious to know about the hobbyhorsing and if there is anything to do to counteract that.

I would suspect that on a finished boat, there really isn't anything one can do, but there has been a lot of research and experimentation done on ama profiles, some of which pertains directly to this. The location of the area of maximum buoyancy, and the relative displacement at the bow and stern, rocker, etc, all contribute here. There are a number of pretty comprehensive articles out there on the net. I unfortunately have not saved any links to them. There is only so much stuff one can save. The 31's are more often open wing than full wing, but I suspect that not many of us are willing to build a pair of amas in hopes that we can dampen out hobbyhorsing. Wave frequency and amplitude are going to make a big difference, as is the speed at which one meets the waves. I have the pleasure of living in an area where there are few paved roads. Once one gets off the highway, you are on dirt or gravel.............Yes there are places like this in America, and I'm the guy you see traveling 65 to 70 on these kinds of roads....... I've never wrecked a vehicle. I look up the street and see a pickup that a teenager rolled because of a sort of hobby horsing. Traveling too fast, he hit washboards. A harmonic resonance is established between the springs, the frame, and the rear axle such that you have no control. It takes front and rear together to steer. If the rear is airborne because of harmonics, the steering wheel does nothing at all. When you finally hit a stretch where you regain rear traction, if the front wheels are not straight with the direction of travel, you are going to roll. The trick, I learned many years ago, is to let go of the wheel more or less.... let it spin in your hands. If you do this, when you hit the other end of the washboards, you will instantly regain control. Much the same scenario as hydroplaning. The point is that the speed of the vehicle or boat passing over the washboards or waves has a huge effect. If you take in sail or hang out more, it should be possible to eliminate or at least reduce the resonance that is hobbyhorsing. That's just my take on it, and may be a load of BS.... but I don't think so. H.W.

[Cavalier MK2]

It is true that the ama shape has a lot to do with it. A CC with the rounded V amas is more stable than the hard chine shape of a SR ama. A shape with the buoyancy down low like a single chine or rounded ama is going to be following the surface contours of the water much more than a deeper V which will be slicing the waves, Main hul shapes contribute too, a symmetrical water plane on a double ender has less pitch resistance than a transom for example.

[slowbat]

Originally Posted by rossad

May I ask some Questions for Trimaran and Searunner folk????
When sailing onto the mooring or off the mooring or sailing onto a wharf or some kind of location and then stop.
Do you have just your main up?
Do you have just your foresail up? which foresail?
Or do you have them both up?
And in what winds strength are you talking about?

Mono's are good with just there main up making things simpler.
I found that.....
The Searunner with the mast position central overall boat length when using the main only gives inadequate drive to windward.
Also having just the staysail or the yankee also doesn't give enough drive pointing higher
So with them both up i found that i can manage to get anywhere.
Any thought about this may I ask.

I sail in/out - on/off with the inner foresail only. It is more balanced and super easy to tack with my cutter.

[slowbat]

Originally Posted by md7a

Thanks to a lot of help from John Prentice I was able to replace the centerboard on Pineapple Express (SR31 #105).
I posted some photos in an album, and shared with the Searunner group.

This was a pretty standard board, built mostly to plans, but a little thin and without the split hose padding -- the original builder made the boat's centerboard trunk narrower than plans, so the old board was always a tight fit.
Here's the remove-build- replace sequence:

Old board stuck in trunk


Old board cut out in pieces


New board shaped to plans



New board with 'glass and epoxy


centerboard pin receiver tube / extension (for replacing pin with boat in the water)

Hey Will,
How is John P doing? Looks like his shop in West Port. Any progress on his 37'?
I went with 2 layers of 3/4 marine mahogany plywood for my boar rebuild this spring. What did you use? and how much glass?

[rossad]

thanks Slowbat and good pics too

[Redreuben]

Hobby-horsing: Without going into serious structural remodelling another remedy could be the T foil rudder, I have no experience personally and wether it's a good fit on this boat or that is up to the individual but if the proponents are to be believed it's a possibility, there is even a kick up design around whereby the foil is hinged to the front of the rudder so it can stay horizontal as the rudder kicks up.

[Redreuben]

Kick up T foil.

Here 'tis,
https://www.catsailor.com/forums/ubb...06508&page=all